To not need fuel would be to have developed a perpetual motion machine. That’s one more rule of physics that would need to be broken beyond the one it’s already claiming.
It doesn’t eject anything to create thrust, but based on the descriptions that I read, it still uses electricity to power itself.
I’m not an expert but it seems all the warp drive and FTL talk is laughable media hype.
BUT they may have discovered an interesting method of propulsion, which is amazing in of itself.
Yes, I said Solar power. Satellites only need occasional small amounts of thrust for station keeping. The solar panels could charge a very large capacitor over a long period and then channel it into the EmDrive for bursts when needed to maintain orbit. Viola, no fuel needed.
No need for name calling! No ones shown signs of being a stringed instrument here. (The word you’re looking for is “voila”.)
“No one’s”.
They’re not claiming to violate conservation of energy, but they are claiming to violate conservation of momentum, which is just as fundamental. And in fact, in relativity, if you can violate one, then there’s going to be a reference frame where you violate the other as well, since they’re both just components of the same four-vector.
My understanding of the drive is that conservation of momentum is not conserved. But also it is THAT a certain interpretation of relativistic effects of electromagnetic radiation under certain rather special conditions is what allows that.
Or in other words, I think they are at least trying to play by the rules as we understand them.
If quantum tunneling and spookey action at a distance can occur, I’m not going to get the vapors to find out momentum isn’t totally conserved as we currently think of it.
I wouldn’t set too much stock by how the creators claim it works. Even if it really does work, their explanation is a confused jumble of mish-mash, and is extremely unlikely to be the actual mechanism.
A friend posted this on FB today. I had never heard anything about it before and assumed it was totally made up. I’m taking it from the discussion here that it is not made up, but will still probably turn out to be a bust like cold fusion in the '80s?
First, that link refers to a 2014 presentation, so it’s nothing new.
Second, yes, it will probably turn out to be a bust – measurement error, mistake in a calculation, forgot to account for metal parts expanding when they heat up, something like that. There’s a small chance (let’s say, now that a real lab has found something, a 1% chance) that there’s something going on that’s completely consistent with current fundamental physics, but still interesting and that we didn’t know about before.
There’s a very very very tiny chance that this is real and will make us revise fundamental laws.
I’d be willing to bet a fair amount of money that it’s a mistake. I’m also skeptical about the sites that are reporting this – ibtimes doesn’t even know how to spell NASA, and as noted, nasaspaceflight.com is unaffiliated with NASA although they seem to be doing their best to hide that fact. Add this to the fact that they’re throwing around terms they clearly don’t understand, like “Quantum Vacuum” and “MagnetoHydroDynamics”, with odd capitalization that no actual scientist would use, and it sure looks like media hype.
–Mark
It’s dated “JULY 27, 2015” and says “Later today, July 27, German scientists will present new experimental results on the controversial, ‘impossible’ EM Drive…”
Independent expert confirms that the “impossible” EM Drive actually works.
There sure seems to be a growing community who believes in this technology, as impossible as it may sound. How the hell do you get propulsion from a sealed cavity?
One thing that is important to understand is that when NASA Eagleworks reports having measured thrust, they don’t actually have a discrete measurement of the thrust load or observed acceleration above a noise floor; the level of thrust this device is purported to develop is far too low for that. Instead, they get mesurements of the angular distortion of a torsional pendulum (that are on the order of a few millionths of a radian or less), calclaute what the nominal gravity and other external loads should be, and then use some kind of a stochastic optimal estimator like a Kalman filter to extract the anomalous thrust from the mean level. What this results in is some estimated level of anomalous thrust at a certain degree of statistical confidence which assumes that you’ve characterized the time-dependent changes in the known external loads to a corresponding degree. And one of the problems with this approach is that if you are looking for a specific trend in the data, you tend to find that trend unless you carefully and critically evaluate both the quantitative quality of the regression and the qualitative difference between your expectation and “random” statististical noise. The upshot is that it is like listening for a whisper in a hurricane and should require repeated and consistent results at independent laboratories before this could really be considered as being a verified measurement much less consistent with some theoretical prediction.
As for the effect itself, a system that could produce net thrust without expelling propellant according to the conservation of momentum would certainly be a violation of physics as we understand it. There are a number proposed variations on this type of resonant caivty drive system (EmDrive, Cannae Drive/Q-Drive, Dean Drive, et cetera), but no consistent or often even coherent theory among the proponents (Robert Shawyer and Guide Fetta each state that the other’s device shouldn’t work with the given configuration, yet both report positive results). Up until now, experimental test data has been sparse and not peer-reviewed and so hasn’t been a credible basis for challenging a basic principle of general relativity (the invariance of proper mass, Lorentz symmetry, and local conservation of momentum) but if anomalous thrust can be independently confirmed as repeatable at the same order of magnitude it would point to a need to reevaluate those dearly held principles, just as the apparently ‘simple’ problems of no measurable bias of the luminiferous aether and the anomalous photoelectric effect ultimate lead to modern physics as we know it (relativity and quantum mechanics, respectively). Although such an extraordinary claim would require extraordinarily rigorous evidence and some coherent theory to back it up, any student of modern physics will admit that we have an enormous gulf of ignorance in connecting gravitation and the field theories that underly the Standard Model (and by implication, gravitational mass and inertial mass) and the fact that all but the most trivial solutions to phenomena in general relativity can only be solved by using a mean field approximation. (This is because of the complexity of the full formulation of the Einstein Field Equations, not that the theory is known to be inherently wrong, but it does allow that even our most precise experimental verifications may have room for additional, more subtle phenomena.)
One interesting suggestion–I won’t call it a theory because it has some substantial leaps of deduction and lack of genuinely falsifiable hypothesis–is laid out in James Woodward’s Making Starships and Stargates: The Science of Interstellar Transport and Absurdly Benign Wormholes as a modification of one interpretation of the so-called Mach’s principle as formulated by Dennis Sciama back in the 1950s; in effect, that the inertial mass of an object is a result of its interactions with the mass of the rest of the universe, and that there can be transient mass fluctuations that can give the appearance as being reactionless change of momentum to the local observer but are no more a violation of global conservation of momentum than a spacecraft performing a gravitational swing-by manuever. However, allowing for this field interaction over non-causal distances requires some massive retooling of general relativity along the lines of Feynman-Wheeler absorber theory, and suggesting that some nonlocal transactional phenomenon (modeled as a standing wave formed by advanced and retarded components going forward and backward in time). Nobody really likes this interpretation in quantum electrodynamic field theory so extending it to gravitation is not a a comfortable pill to swallow. Anyway, Woodward, like other researchers, has claimed to have demonstrated effects consistent with this theory but not in a peer-reviewed or independently verified format, so we can take his proposed effect (which again does not yet rise to the degree of qualification to be considered a falsifiable theory) with a grain of sodium chloride.
The sum total is that there are plausible explanations for why this effect may occur and experiemental results could be genuine (or at least reflect something other than just pure measurement error), and certainly value in spending a very small amount of funding (compared to the overall NASA budget) to evaluate them in more detail, but we are still far from declaring that Einstein relativity is dead. I’m inclined to give the current experiements a little more than just 1% chance of being something other than measurement error (more out of hopeful optimism than rigorous methodological evaluation) but not anywhere close to breaking out the champaign or planning a trip to Betelgeuse. And even if the effect is real, there may be practical limits to the extend or efficiency of thrust than can be produced that may render it more of a novelty or applications such as high orbit stationkeeping than general propulsion.
Stranger
Very interesting, thanks Stranger.
Fight my ignorance here. Isn’t this device supposed to be producing thrust by expelling radiation? That is, energy? If so, how is the issue problematic?
It’s a closed device. The radiation bounces around the inside and somehow causes net thrust.
Even if the RF photons somehow made their way out, though, the thrust levels claimed are way higher than what you would expect from a photon drive. And if you can build a propellantless drive more efficient than a photon drive, then you can build a free energy generator.
Given it has an exhaust, how is it a closed device?
There’s no exhaust. It has a bell shape which superficially resembles a traditional rocket engine, but the end is closed. See this picture, for instance.
The EmDrive (and the Cannae drive) don’t have any exhaust; they’re a closed chamber which is shaped to create a resonant condition on microwave frequency radiation emitted into it. (The Q-drive does have an exhaust but not propellant input; the propellant is supposedly virtual particles to which momentum is transferred and ejected, acting in the traditional rocket propulsion manner except that that the vehicle doesn’t carry the propellant along with it and is no longer limited by specific impulse limitations.)
One explanation that is advanced is that the reflected and amplified waves in the chamber act upon the “virtual particle plasma” in a biased fashion, resulting in net thrust, and the complementary momentum presumably being applied to the quantum vacuum background field or whatever. The problem with this explanation is that in the aggregate virtual particle pairs produced by the the quantum vacuum necessarily have a net charge of zero and thus don’t act like a plasma or could provide net thrust from EM interactions alone, nor does this really explain the transfer of momentum in a global context. (Note that we don’t have to assume global conservation of momentum and in fact it probably isn’t even sensible to talk about in a presumably open and effectively infinite universe, but we would like for the bookkeeping to work out lest we start having to indulge in free energy and other madness that would make an absurdist Shakespearean comedy of all of our laws of physics.)
Getting back to the measurement problem, poking around the Internet a bit came up with this plot of the thrust levels observed in one test. (The plot is dated 31 January 2015 so it is fairly recent.) Note that while the scale of the force measurement is in newtons (with the increments in millinewtons) the supposed anomalous thrust extractions is 54 micronewtons. While the RMS value of the F[sub]z[/sub] component looks to be about 1 mN and varies wildly, the predicted thrust is ~54 micronewtons, an order and a half of magnitude less than the disturbances. At those levels I’m surpised they are willing to draw any conclusions about the anomalous thrust, and unless it is an aboslutely steady thrust level I question the ability to extract a thrust to any useful degree of confidence. I’d like to believe there is something here because it would be interesting, but I think it is premature to draw any conclusions until indepenent peer review and reproduction of the results has been demonstrated.
Stranger
